Re: [I] HA : Hosts persist in the Suspect state in HA cluster with ShareMountPoint [cloudstack]

["Luskan777 (via GitHub)" <gi...@apache.org>]

Luskan777 commented on issue #10166:
URL: https://github.com/apache/cloudstack/issues/10166#issuecomment-2813199583

   Hello everyone,
   
   With some changes, I managed to add HA support for ShareMountPoint volumes. My changes are in this [fork](https://github.com/apache/cloudstack/compare/main...Platon-Cloud:cloudstack:add-support-ha-sharemountpoint) I made.
   
   I tested it and it worked perfectly, however, I believe these commits are not ready for Pull Request, because during development, I identified a limitation in the way Cloudstack handles the ShareMountPoint storage type in Libvirt.
   
   Cloudstack uses the same storage pool format for ShareMountPoint and Filesystem, that is, both StoragePoolTypes use Libvirt [Directory Pool](https://libvirt.org/storage.html#directory-pool).
   
   Therefore, in lower layers of Cloudstack, especially when dealing with Libvirt StoragePools, the ShareMountPoint type becomes the Filesystem type, which is a problem, since the Filesystem storage type is not shared and does not allow HA because it is a local storage.
   
   https://github.com/apache/cloudstack/blob/55c811547a8c516c065c99f4d1ede5f43913c4c1/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java#L318-L324
   
   https://github.com/apache/cloudstack/blob/55c811547a8c516c065c99f4d1ede5f43913c4c1/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java#L827-L828
   
   To solve this (temporarily), I created some conditions to enable HA on the Filesystem storage, as per the code below:
   
   https://github.com/Platon-Cloud/cloudstack/blob/ce34c03f30686e4e186ab1459a81f46bd5230279/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStoragePool.java#L318-L321
   
   To avoid conflicts between what is the Filesystem storage and what is the **ShareMountPoint**, I created the condition that checks if the storage path is the same as the LOCAL_STORAGE_PATH configuration variable. THIS IS FAR FROM THE BEST SOLUTION, but it solves the problem for now.
   
   As a definitive solution, I think it would be interesting to open a discussion to change the Libvirt StoragePool format used for ShareMountPoint. My recommendation is to change it to the [Filesystem pool](https://libvirt.org/storage.html#filesystem-pool) format. Using this format makes sense for the ShareMountPoint storage type, and I also haven't found any other StoragePoolType that uses this Libvirt storage format.
   
   Since this is a change that I consider relevant, I decided to consult the community before developing it. If the community decides that it makes sense to change the Libvirt storage format from ShareMountPoint, I'll be happy to develop it.


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